Step 1: Find Your Size
How do you know what size tires you're currently running? Easy—check the tire sidewall. For road tires, you'll probably see a number pairing such as 700x23. The first number (700) is a size which roughly corresponds to the diameter of the tire in millimeters. The second number (23) denotes the actual tire width in millimeters. For mountain bike tires, you'll see a number pairing that looks like 26x2.0. This is the actual bead-to-bead diameter (26 inches) by the width (2 inches).
You don't have to buy the exact width that you currently have. You might want different sizing for improved stability or grip. But you generally shouldn't veer too far from what you have, since this can create performance or durability issues.
Road touring and racing: Most road tires today are the 700 size (sometimes called 700C). Exceptions include a few 650s (used on front wheels for faster acceleration and/or for smaller riders to decrease stand-over clearance) and the 27" size used on older bikes. Check the wheel rims for sizing — if you can't find the circumference, bring it to a bike shop to have a sales rep confirm what tire size you need, because it's difficult to accurately measure circumference without special tools. Most racers and others devoted to velocity run 700 tires in widths ranging from 18 to 23 millimeters — the narrrowest options. Those who live for epic tours are more likely to be riding tires in widths ranging from 25 to 28 millimeters for a bit more stability and comfort.
Mountain biking: Mountain bikes traditionally sport a 26" tire diameter. A cross-country or all-mountain bike will have tires in the 1.8" to 2.4" width range. But freeride and downhill bikes, which are meant to withstand the abuse of drops and rock gardens, are equipped with tires ranging from 2.5" to 3.0" in width.
29ers: 29er mountain bikes have really caught on in recent years. They run a wider, knobbier variation of the 700 tires used for cyclocross, but otherwise look like your typical mountain bike tire. 29ers are touted as being able to roll more easily over technical trail sections and through mud and sand. Cornering and climbing traction are also said to be better due to the fact that "big wheels" offer more contact with the trail.
Other uses: Cyclocross tires have small knobbies but are designed in a narrow-width 700 size to fit the geometry of cyclocross racing frames. BMX tires usually come in a 20" diameter.
Step 2: What Surfaces Do You Ride?
If you ride on asphalt or other hard, even surfaces, slicks are your best bet. The smooth surface of these tires offers maximum velocity for minimum effort, but they still offer enough grip in most conditions.
If you ride on a combination of surfaces, including concrete, asphalt, smooth singletrack and/or the occasional stretch of gravel, either cyclocross tires (for road-specific rims) or semi-slicks (for either road or mountain bike rims) are optimal solutions.
Dirt riders definitely need a mountain bike tire for traction in variable conditions. If you expect to ride primarily on one type of terrain, choose a tire designed for that surface. This can vary depending on your part of the country. For example:
- Relatively smooth Moab slickrock does not require an aggressive tread pattern.
- Muddy, rooty Pacific Northwest trails demand a tire that's not only more aggressive, but one that has wider-spaced knobbies to shed mud.
- Wider-spaced knobbies usually offer the most versatility.
Unsure? Ask your local bike shop pro or peruse tire manufacturer websites to find tires designed for your favorite riding terrain.
Step 3: Choose a Tread
Tread is an important issue for any tire, but especially for knobby mountain-bike tires, where small differences in the tread pattern can result in a significantly different ride. More tread typically means more grip—but also more rolling resistance. So you'll need to balance your need for speed with your desire for grip.
No matter what type of rider you are, sharp tread edges are a must. When they're worn down to the point where you're getting lots of flats, your bike is handling poorly and/or the tread appears rounded or uneven, replace your tires to guarantee more fun and more safety. When you see the casing threads below the rubber, you've waited too long.
No matter what type of rider you are, sharp tread edges are a must. When they're worn down to the point where you're getting lots of flats, your bike is handling poorly and/or the tread appears rounded or uneven, replace your tires to guarantee more fun and more safety. When you see the casing threads below the rubber, you've waited too long.
Road tires are less complicated. Front- and rear-specific treads are often sold as sets. And because road tires grip the irregularities in pavement, you won't see as many tread variations as you will with mountain-bike tires.
Other Bike Tire Considerations
Soft or Hard Rubber?
Most tires use primarily one type of rubber. At one end of this spectrum is soft, sticky rubber. These are your grippier choices. At the other end is hard rubber, which is more durable. Most riders determine what type of tire to buy based on budget (how often can I afford to replace tires?) and performance (how much control do I need on my favorite trail or road?).
High-performance riders might want to consider dual-compound rubber tires. These feature a softer rubber on the outside that contacts the ground, and a harder rubber between the tread and the casing. The result? Better grip and better cornering in almost any terrain.
Thread Count Casing (TPI)
Thread counts have the most impact in road uses, where tire pressure is higher. According to bike tech Mike from REI's Seattle store, "A higher thread count casing makes (the tire) suppler and more resistant to punctures and makes it a little lighter."
Thread counts for a road clincher start at 60 tpi (threads per inch) and go up to 320 tpi for higher-performance clinchers or tubular tires used in racing. Other tires have thread counts as low as 20 tpi. Check the specs tab on REI.com product pages to compare different tires.
Foldable Tires
These tires often have an aramid-fiber bead (such as Kevlar®) instead of a wire bead. This makes them light and foldable for easy transport and storage. Foldable tires are available for both mountain bike and road riding. The downside is that they are usually more expensive.
Tubeless Tires
These are popular with racers and high-performance riders. The pros? Depending on your weight and the terrain, you can run lower tire pressures—down to 20 psi—for better traction without pinch flats. Plus, the ride tends to be smoother. The cons? You can't use tire levers to ease the install process, and you may still want to carry a tube because fixing a tubeless flat is more complicated than on a conventional tire. Some tire makers simply recommend that sealants be used to fill a tubeless flat.
Keep in mind you need to have tire rims designed for this technology unless you invest in a system that converts traditional tires and tubes to tubeless. More tubeless tires are available for mountain biking than road riding. The cost? They usually run $50 or more apiece.
Tubes
Tips on Tire Pressure
Every tire has a preferred pressure range, which is measured in psi (pounds per square inch). Look on the tire sidewall for the recommended pressure. In general:
- Road tires should typically run on 100 to 140 psi.
- Mountain bike tires should typically be 30 to 50 psi.
Lower pressures can improve traction almost as much as good tread and good technique, but inflate your tires too little and you'll have problems with pinch flats. Inflate them too much and you'll either experience less stability (the best case scenario) or blow out the tube (worst case scenario). Higher pressures result in more speed with less effort but they also offer less traction.
Higher-end tire pumps will have a psi gauge, but if you have a lower-end pump, you'll need to carry your own tire pressure gauge.
Ways to Reduce Flats
While no tire is completely puncture-proof, there are some options that greatly reduce your likelihood of getting a flat. The downside of these is that they add a bit of weight.
Puncture-resistant Tires
These tires won't feel as speedy as standard bike tires, but commuting customers have told us that they experience flats much less frequently (reportedly up to 7 times less) when using these tires. The reason? Many tires makers employ a durable belt of aramid fibers (such as the well-known Kevlar® brand) to resist punctures; others simply increase the tread thickness. These tires are marketed by a variety of proprietary names: the Serfas Flat Protection System, the Continental Safety System, the Panaracer Protex Shield and so on.
Tire Liners
Flat Sealants
Some commuter tires feature small knobbies, but they aren't really necessary unless you're taking side routes through the dirt or gravel. Keep in mind that small knobbies are quicker to wear down to the point of being unusable than their slick or inverted-tread counterparts. Smooth-rolling tread designs are speedier and tend to be more stable through turns.
Puncture-resistant tires (described above) offer a flat protection layer built in under the tread of the tire. This added layer offers increased protection against flats from debris, thorns and broken glass.
The Cross-Country Rider
Because you live for long epic rides, the weight of your tires (and every other component) is often a major consideration when outfitting or upgrading your steed. Consequently, narrower knobby tires ranging in width from 1.8" to 2.4" are usually a perfect fit for this type of riding. Racers are most likely to run tires less than 2" in width, while most other cross-country riders opt for tires in the 2" to 2.4" range for more versatility. Beyond weight and width, you'll want to look at the type of terrain you're riding. Mellow singletrack and slickrock require a much different tire than mud or rooty, technical terrain (see the tread and sizing sections of this article for more info).
The Freeride/Downhill Mountain Biker
Tires that grip on sketchy, steep chutes and rock gardens and survive hours of big drops at Whistler or other mountain-bike parks are ideal for freeriding. Look for aggressive tread patterns with tall knobbies. Softer sticky-rubber compounds will grip almost anything to help you rail corners and survive those treacherous double-blacks, but they'll wear out more quickly so prepare your budget accordingly! Most tires of this type will specifically mention "sticky rubber" or "silica" in their ads, but ask your friendly bike shop pro to be sure.
Expect to buy tires in the 2.5" to 3" range for maximum hucking performance.
The Road Explorer
Road racing and touring are entirely different worlds, so the demands on your tires are different. Road warriors should choose skinnier tires for a more nimble ride or a wider tire for more stability. If you're carrying a load, you will want a somewhat wider tire than you would otherwise run.
If you're a racer, look for the lightest, speediest tire possible with great grip for cornering ability in your next criterium.
Those of you who are touring cyclists will still want something relatively speedy, so that you're not still spinning down country roads after dark. But comfort and flat-proofing are also major considerations. Typical widths for touring are 32 or 35 millimeters on a 700 tire.
Bike Tire FAQs
Q: How do I know what size tire to buy?
A: This is your foremost tire-shopping consideration.
- Determine the size of your rim: You don't want a tire that's significantly wider or narrower than your rim. Some manufacturers offer information about recommended tire widths for their rims on their Web sites or marketing brochures. Checking with the folks at your local REI or other bike shop is another way to get accurate information about optimal tire widths for your rim.
- Consider your typical riding terrain: Would you benefit from the increased stability of a wider tire?
- Look at your riding style: Are you a climber who wants a narrower tire or are you a bigger rider who plans on long touring expeditions requiring a wider tire?
Q: What is the most versatile type of tire for commuting?
A: Tires with a slick or inverted tread will speed you across asphalt. Those with small knobs might slow you down a bit but give more traction if you hit some gravel or dirt along the way. A medium-width tire (28mm to 32mm or 1.5" to 1.75") offers the best mix of speed and comfort, neither slowing you down nor leaving you exhausted because of road shock (i.e., the impact on your body from rolling over the road).
Q: Can I use the same mountain bike tire in dry and muddy conditions?
A: You can, but performance won't be optimal in either condition. If you're new to the sport and/or have a limited budget, opt for an all-purpose tire or buy a tire that best corresponds to your typical terrain.
Q: Do I have to buy new tubes with my new tires?
A: Almost always. A tube will conform to the tire surrounding it. According to bike tech Mike at the REI Seattle store, "Even though this tube may have been a 1.5" to 2", if it's been in a 2" tire for 6 months, 8 months or 2 years, it's not gonna go back and fit in a 1.5" again. If you know that ahead of time, you can save a lot of time, because if you try to stuff that tire back in there, that's nearly impossible."
Q: What can I do to avoid flats?
A: Here are several tips from the REI bike techs:
- Always run the pressure recommended on the sidewall of your tire.
- Use puncture-resistance tires.
- Add a tire liner between your tire and tube.
- Consider tires with a high thread-count casing (measured as threads per inch, or tpi)
- Always carry a flat repair kit or sealant for those times when all your precautions don't help.
Bike Tire Glossary
Bead: The edge of the tire that holds the tire onto the rim. Wire beads cost less but aramid beads such as Kevlar® offer flexibility that allows the tires to be foldable and offer weight savings of up to 50 grams per tire.
Clincher tires: A tire where the bead "clinches" the rim, held in place by air pressure. Roughly 95% of bike tires are this type.
Kevlar: An aramid synthetic fiber material used for durability and flexibility in tire beads and flat protection panels.
Pinch flats: Flats caused when the tube is pinched between the rim and a sharp or hard object. Inflating your tires to their suggested pressure almost alleviates this problem.
Psi: Pounds per square inch, a measurement of tire pressure.
Rolling resistance: Friction created when tires roll. Rubber compounds, tread patterns and tire pressure all impact rolling resistance, with softer rubber, lower tread and higher pressure all creating less.
Tpi: Threads per square inch, a measurement of tire thread counts. Higher-thread-count tires (120 to 160 tpi) tend to be more puncture-resistant, lighter and expensive, whereas lower thread counts (20 to 30 tpi) equate to lower prices, a bit more bulk and a bit less durability.
Tubular tires: Also known as sew-ups, these tires are used primarily for racing. Tubes are sewn inside the tire, which is then glued onto a tubular-specific rim.












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